Dec. 5, 2012 -- Many parents might good-naturedly scoff at the notion, but a new study shows that being a parent may help you live longer.

Danish researchers compared men and women who had children with those who did not to see if the childless were more likely to die early.

They were. "Childless couples are at increased risk of dying early of all causes," says researcher Esben Agerbo, PhD, associate professor at Aarhus University in Aarhus, Denmark.

The benefit of parenthood on longevity was stronger for women than for men, says Agerbo.

The study findings echo those of previous research. It is published in the Journal of Epidemiology and Community Health.

Children & Longevity: Details

Agerbo used health and social registers in Denmark. He focused on more than 21,000 childless couples who registered for IVF treatment between 1994 and 2005.

He followed them from the time they began IVF treatment until the end of 2008, their death, their emigration, or a diagnosis of mental illness, another link he was exploring.

During the time period, more than 15,000 babies were born. Another 1,564 were adopted.

Death was rare. During the study period, 96 women and 220 men died. Parenthood apparently decreased the risk of early death. Mothers with a biological child were four times less likely to die an early death than childless women.

Fathers with a biological child were two times less likely to die an early death than childless men.

Men who adopted were nearly half as likely to die early as men who had no children.

For women, the effect of adoption on longevity was not significant, Agerbo says.

Explaining the Parenthood & Longevity Link

Agerbo says he found a link, not a proven cause and effect.

He can only speculate as to why parenthood may increase longevity.

''My best guess is health behaviors," he says. "When people have kids, they tend to live healthier."

They pay more attention, he says, to lifestyle habits. For instance, they may get to bed earlier and get more sleep, knowing they have to get up early to feed children and do other tasks.

Parenthood & Longevity: Perspective

The new findings echo those of Michael Eisenberg, MD, director of male reproductive medicine and surgery at Stanford University.

In a study published in 2011, he found that childless married men had a higher risk of dying from heart disease acquired after age 50 than did men with two or more children.

The new study findings, he says, are ''certainly consistent with the identified link between childlessness and cardiovascular mortality."

As for how to explain the link, he says, "our group [of researchers] subscribes to a biologic link."

He says that fertility problems, common among the childless, may share some of the same origins as other health problems.